After improving my animation, render time has increased drastically
here you can find a way to check what area of the screen takes more to render:
https://blenderartists.org/t/any-way-to-generate-a-render-time-heatmap/1161497

Render layers node is used in combination with Color ramp to show the longer pixels to render.

Another way to check what is slowing down your render is to disable all objects and re-enable one by one and check render time (and eventually crashed too).